A laser camera used for tracking, monitoring or inspection of laser or arc welding has one or more transparent windows or lenses that transmit optical signals in or out of the camera enclosure. Such a laser camera is often used in robotic processes and requires protection for long periods of welding against welding fumes that could contaminate the transparent windows or lenses. External air knifes or jets are often used to protect these windows or lenses against contaminating welding fumes or other contamination. U.S. Pat. No. 4,859,829 (Dufour), U.S. Pat. No. 5,264,678 (Powell et al.), U.S. Pat. No. 5,442,155 (Nihei et al.), U.S. Pat. No. 6,270,222 (Herpst) and U.S. Pat. No. 7,557,326 (Boillot et al.) provide examples of laser cameras of the prior art, some of which including protection against welding fumes. In the prior art, the camera windows or lenses are sometimes protected by air jet covering only a partial portion of the aperture contour, as illustrated on FIG. 7. In such prior art devices, air pressure is applied on the internal surface of a protective plate of the window and notches on the other side of the protective plate, covering only a part of the aperture contour, allow air to escape outside as depicted by the arrows in FIG. 7. Such a construction provides only partial protection of the window area and unsatisfactory long term protection, especially for large and numerous apertures. Also, fluctuating air pressure sometimes causes undesired vibration of the protective plate in the window and rapid contamination and even detrimental suction of the contaminating fumes toward the optical sensors of the laser camera, especially when different plates are used to replace the initial plate.